1. Field of the Invention
The present invention generally relates to a new and improved end treatment for roadside barriers. The invention is especially suited for use with a barrier which is commonly referred to as a "low profile road barrier." The end treatment features sidewalls which angle outwardly from its base so as to reduce ramp and roll tendencies of vehicles impacting on it from the side.
2. Description of the Prior Art
Along most highways, there are hazards that present substantial danger to drivers of automobiles if they should happen to leave the highway. To help prevent such accidents, road barriers are often provided along the sides and in the median of a highway to channel the vehicles into appropriate lanes.
The use of road barriers has several important purposes. First, as noted above, the barriers are intended to channel vehicles hitting the barriers back into the adjacent traffic lanes. Second, the barriers are intended to help prevent vehicles from traveling entirely off the road or into the lanes of opposing traffic.
The common types of roadside barriers are structural concrete barriers and guardrail barriers. A typical structural concrete barrier is the "CMB" barrier which is about two feet wide at its base and tapers inwardly to a height of about 32 inches. The barrier at its top is typically about 6 inches wide. The guardrail barrier typically consists of treated wood posts placed periodically in the ground in an upright position with sections of corrugated metal connected horizontally to the posts.
Another type of roadside barrier is the low profile concrete road barrier described in application 07/691,392 filed Apr. 2, 1991, which has been incorporated herein by reference. The low profile concrete road barrier is typically comprised of one or more segments of structural reinforced concrete which measure no more than about 24 inches in height, and haveuter sidewalls facing the road which angle outwardly from the barrier base. The upwardly outward angle of the sidewall helps to make vehicle collisions with the barrier safer by reducing deflection off the barrier. The angle also reduces the rolling and ramping of vehicles impacting the barrier by tending to redirect the vehicles back onto the roadway and prevent such vehicles from mounting the curb.
End treatments are used generally on various roadside structures for safety purposes. One type of end treatment provides a gradual slope at the end of a roadside structure. This gradual slope helps to prevent head-on collisions by automobiles into the end of the structure. The gradual slope allows the automobile to move up on the structure which is a safer alternative than a head-on collision. Sloping end treatments are most commonly used in conjunction with guardrails, concrete barriers and drainage structures along roadways.
Another type of end treatment used in conjunction with a guardrail or concrete barrier usually consists of simply tapering the height of the rail or barrier downwards until it matches the existing natural ground elevation. The end treatment, when used with drainage structures, usually consists of reinforced concrete which is formed around the sloped-end of a pipe or culvert.
Neither of these two end treatments, however, is especially suitable for use in conjunction with the previously described low profile concrete road barrier. Moreover, both of the end treatments suffer from the same shortcomings as the conventional guardrail and CMB barriers.